Replaced the engine (conn rod knock) with one from a 2003 auto. Block is pretty much identical. I swapped/replaced all external and marine specific parts then disposed of the old block and internals since I had no place to keep it.......

Upon installation of the new engine, I realize the new motor has an oil filter mounting assembly that incorporates an oil cooler, which of course the old motor did not. After removing the oil cooler assy, there's no nipple on which to thread an oil filter. I've temporarily solved the problem by connecting the oil cooler's in/out lines, but I know I'm adding additional potential failure points.

Is there an adapter with a nipple still on my old block? And if so, how can I find a new one to install on the new engine? GM has one but the bolt spacing is wrong.

Thanks in advance, and thanks for not asking questions about whether I modified the new engine for marine use. I did.

I was provided 2 round plate mounted adapters w/ nipples that were supposed to bolt on in place of the oil cooler assy. Neither worked. GM dealer didn't show any SB 4.3's without a factory oil cooler... The suggestion now is that the nipple may unthread from the assembly and thread straight into the block - no bolts, no adapters. I curse myself for not triple checking the old block.